Combined pitch lock and feather latch



June 8, 1965 P. E. BARNES ETAL 3,187,819

COMBINED PITCH LOCK AND FEATHER LATCH Filed April 29, 1963 3 Sheets-Sheet 1 ATTORNEY June 8, 1965 P. E. BARNES ETAL 3,187,819

COMBINED PITCH LOCK AND FEATHER LATCH Filed April 29, less 3 Sheets-Sheet 2 FIC3-2 maul 4.5 ""gnmg IIIIIIIII INVENTOR PHILIP E- JOHNQSILLI Maw ATTORNEY June 1965 P. E. BARNES ETAL 3,187,819

COMBINED PITCH LOCK AND FEATHER LATCH Filed April 29, 1965 3 Sheets-Sheet 3 FIGJI l- IGJA- 7 BY ATTORNEY United States Patent CfllvlBlNED PITCH LGCK AND FEATHER LATCH Philip E. Barnes, North Granby, and .lohn B. Silliman,

West Hartford, 60:211., assignors to United Aircraft Corporation, East Hartford, (30:111., a corporation of Delaware Filed Apr. 29, 1963, Ser. No. 276,499 18 Claims. (Cl. 170l60.24)

The indicated extent of these ranges are given as an example and not as .a limitation. A motor of any suitable type, such as hydraulic or electric, may be used to change the propeller pitch. In the event of malfunctioning of the motor, such as failure of its power source or failure of the motor itself, while operating in the normal range, it is desireable to prevent the propeller blades from following their inherent tendency to move toward low pitch and therefor automatically actuating pitch lock mechanism is provided which will prevent further pitch reduction but will permit a pitch increase. \Vhen the blades are in feathered position aerodynamic forces under certain conditions have a tendency to urge the blades toward a lower pitch and therefore latching means are provided to assist in holding the blades in their feathered position. This latching means should, however, be of a friction or a friction and spring type of device so that the pitch changing motor may if desired overcome the latching eifect and reduce the propeller pitch and it is desirable that the latching mechanism be moved to unlatched position by latch releasing mechanism before the pitch changing motor is activated when it is desired to take the propeller out of its feathered position down into the operating range. When passing from the operating range through the major portion of the feathering range and also through the entire reverse range it is desirable to render both the pitch lock mechanism and the feather latch mechanism inoperative.

It is an object of this invention to provide a combined pitch lock and improved feather latch.

Other and additional objects and advantages will be apparent from the following specification and the attached drawings in which: 7 7

FIG. 1 is a side elevation, partially in section and showing our invention in the now preferred embodiment of a variable pitch aircraft propeller;

FIGS. 2-6 are perspective views showing the combined pitch lock and feather latch in several different operative positions;

FIG. 2 shows a lock and latch held apart by the cams;

FIG. 3 shows the feather latch in operative position;

FIG. 4 shows the lock, the latch and the cams held apart by'the normal operating fluid pressure;

FIG.'5 shows the pitch lock in operative position;

FIG. 6 shows the cams in operative position in the reverse pitch range;

FIGS. 7, 8, 9 and are composite sections taken through the lock teeth, the latch teeth and the cam to show their relative relation in the several operation positions;

FIG. 7 corresponds to FIG. 2 showing the cams in operative position in the feathering or reverse ranges;

FIG. 8 like FIG. 3 shows the latch in operative position;

FIG. 9 like FIG. 4 shows the latch, lock and cam members held apart by the normal fluid pressure;

FIG. 10 like FIG. 5 shows the pitch lock in operative position;

FIG. 11 is a partial end view of the axially movable locking and latching member;

FIG. 12 is a partial end view of the rotatable locking and latching member;

FIG. 13 is an enlarged side View of the locking and latching teeth, showing the locking teeth within the envelope of the latching teeth; and

FIG. 14 is a developed view showing the relation of the cams, the locking teeth and the latching teeth, with the pitch lock teeth engaged.

This invention is an improvement on the structures shown in Patent No. 2,791,283 issued May 7, 1957, to Raymond P. Lambeck for Feathering Detent and Patent No. 2,940,527 issued June 14, 1960, to Harold L. Van Alstyne and Marshall B. Thornton for Propeller Pitch Lock Disabling and Feather Lock Mechanism to which reference maybe made for further details of the propeller pitch lock actuating mechanism and its controls and for general propeller structure. While the lock and latch mechanism of the present invention is suitable for use in many types of hydraulically controlled propellers including that shown in Patent No. 2,940,527 referred to above, for purposes of explaining the present invention it is shown in a propeller having a somewhat dilferent type of pitch changing mechanism. In the embodiment selected for purposes of explaining the invention two rows of propeller blades it) and 12 are mounted in a single hub for pitch changing motion about the individual .blade axes 16 and i8 and for rotation about the propeller hub axis 2%). The blades are mounted in the hub for pitch changing movement by any well known means such as the ball bearings 22. A hydraulically actuated piston 24, operating in the.

usual manner by the preponderance of oil pressure on one side or the other of the piston which oil pressure, is controlled in any suitable and well known manner by any of the well known mechanisms used in controllable pitch propellers for controlling the propeller pitch such as that shown and referred to in Newton et al. Patent 2,998,849 issued September 5, 1961. Secured to the piston 24 by means of a sleeve 26 is a cam sleeve 28 movable axially along the axis 20 of the hub 14 by the piston 24 and having cam slots 39 cooperating with rollers 32 carried by the propeller blades .19 for changing the propeller pitch. Suitable means such as a longitudinal slot in the cam sleeve 28 cooperating with a roller, not shown, fixed in the hub 14 will serve to prevent the cam sleeve from rotation within the hub. Also adjustably fixed to the pis- 7 ton 24 by means of serrated rings 3-4 is a sleeve 36 having external spiral splines 38 thereon. These external spiral splines mate with corresponding internal spiral splines on a rotatably mounted sleeve 40 rotatably mounted in a sleeve 41 fixed to the hub 14. Reciprocating motion of the piston .24 will, by means of the spiral splines 38 impart rotary motion to the sleeve 40. Fixed on sleeve 40 and rotatabletherewith is one-half of the lock and latch mechanism indicated generally at 42 and forming part of this invention. The other part of the pitch lock and latch mechanism indicated generally at 44 is fixed .against rotation in the hub by means of splines 46. The portion 44 is urged as aunit toward the portion 42 by a compression spring 48 and is held out of contact with the elements of the portion 42 by the introduction of oil pressure into the chamber 50 of a single acting motor. The oil to chamber 50 is led to the chamber through channels 52 and 54 and may be controlled in any suitable and well known manner such as by overspeed governor devices or other control mechanisms now Well known and explained in the Van Alstyne Patent 2,940,527 and the patents referred to therein. In the well known manner of operation of a single acting hydraulic motor oil pressure in cham- 3; ber 50 will move piston 51 to the left and part 44 against stop 75 in the hub and hold the parts 42 and 44 separated and upon failure of that oil pressure thespring 48 will force the parts 42 and 44' into meshing engagement.

Each of the elements 42, 44 comprises three concentric circles of cooperating elements. The outer circle comprises a complete circle of undercut pitch lock teeth 56 and 58. The middle circle or ring comprises interrupted sets of saw teeth or serrations 6%, 62 having ratchet slopes 61 on one side and a latching slope 63 on the other-see FIG. 13. These latching slopes are not undercut so the elements 42, 44 may be separated from the latched position under load by the introduction or" pressure into chamber 56. The inner circle or ring comprises interrupted cams 64 and 66.

As shown in FIG. 4 and FIG. 9 when the chamber St? is filled with oil under pressure all of the elements of the members 42 and 44 are held out of contact or mating relation in all rotary positions of the portion 42. This is the normal position and relation of the elements while the propeller is operating in its normal or operating range between low pitch position and high pitch position and the portion 42 of the pitch lock and latch mechanism is freely rotated on its axis. While in this range failure of oil pressure will cause the spring 43 to force the pitch lock 55 and 58 into meshing engagement as shown in FIGS. 5 and 10. As shown in FIG. 7 cam members 64 and 66 have a slightly greater axial extent from the members 42 and 44 than either the feather latch teeth 69. and 62 or the pitch lock teeth 56 and 58. It will be noted that the feather latch teeth ea, (2 have substantially the same axial extent as the pitch lock teeth 56, 58, so that the tops 67 of the latch teeth lie in substantially the same plane as the tops 69 of the lock teeth. Due to the shape of the latch teeth they have a smaller tooth height than the lock teeth. The teeth are indexed so that complete or partial meshing of the latch teeth at 62 will prevent meshing of the lock teeth 56, 58. It is thus obvious that when either the cam 64, 66 or the feather latch teeth 60, 62 are in meshing engagement that the pitch lock teeth 56, 58 are held out of engagement. In order that the pitch lock teeth 56, 58 may engage it is necessary that the rings which include the feather latch teeth be recessed at 68 and 7G to provide clearance for the feather latch teeth 62 and 69 in the propeller operating range and that the.

ring which includes the cams 64 and 66 be similarly recessed at 72 and 74 to provide clearance for the cams 64 and 76 in the operating range. This clearance is also shown in FIG. 10.

After passing the high pitch position of say 62 in moving the propeller towards feather position earns 64 and 66 are positioned in operative opposed positions by rotary movement of the member 42 and in the event of failure of oil pressure in chamber 50 serve to prevent partial engagement of the latch teeth 6%, 62 or engagement when partially juxtaposed by holding the latch teeth separated as shown in FIG. 7 until the latch teeth are moved by the member 42, which is moved in timed relation with the blade pitch movements, and the latch elements 66, 62 are juxtaposed and in a position for complete engagement. Thus even failure of the oil pressure in the chamber 50 cannot cause partial engagement of the feather latch teeth. Upon reaching the feathered position which may be determined by adjustable stops, not shown, the pressure in chamber 58 may be drained by either manual or automatic means such as shown in Pearl Patent 2,703,148 particularly in the paragraph beginning in line 17 of column 4, and the feather latch teeth permitted to engage. The angle of the feather latch teeth is such that they will provide sufficient friction or friction plus spring force to hold the propeller blades in their feathered position still they may if desired be overcome by theforce of the pitch changing piston and the feathered position of the blades either increased or decreased with the feather latch members engaged. A sequencing valve, not shown, similar to that shown at 100 in Newton patent referred to above is preferably provided so that introduction of low pitch pressure oil will first pressurize chamber 59 before it becomes elfective to actuate piston 24 to reduce pitch. Hence the member 4-4 will be moved away from member 4-2 and the teeth 64 and 62 moved out of meshing engagement i.e. unlatched, so that member 42 may rotate freely before any pitch changing movement is initiated. Although the two members fitl and 62 have been shown in FIG. 3 to be of substantially equal circumferential extent it will be appreciated that one of the sets of teeth may be of a greater circumferential extent than the other so as to permit complete engagement of the smaller set with the lon er set over a limited pitch range. By using such a series of small teeth adequate surface is provided both for strength and wear and a fine adjustment of the feathered position is provided. Adjustments of one tooth spacing, which may be of the order of one-half of one degree, may be made in the feathered position. The large number of small teeth will have a comparatively small axial dimension and hence require a comparatively small axial movement for complete disengagement of the feather latch. The necessary separation, or the axial distance between the pitch lock teeth 56 and 58, in thenormal operating range of the propeller is determined by the stop 75 and is made up of the clearance between the cam members 64 656 and the slight additional clearance between the feather latch members 60, 62 and the working clearance between the teeth 5-5 and 58 which is substantially the same as the clearance between the feather latch teeth 6'3, 62 all of which are shown exaggerated in FIGS. 7-9 and 14. The clearance between the cam members may be only a few thousandths of an inch to assure that the cam may be readily and freely moved into operative position and the clearance between the pitch lock teeth 55 and 58 and the feather latch teeth 60, 62 need be only a few thousandths of an inch. To assure that the pitch lock teeth 56, 53 will not make contact when the feather latch teeth 60, 62 are in meshing engagement both sets of teeth are given the same pitch and are indexed and shaped so that the pitch lock teeth lie within the envelope of the pitch latch teeth as shown in FIG. 13 or are indexed and spaced so that when the tops of the feather latch teeth are in contact the tops of the pitch lock teeth are juxtaposed either in contact or slightly spaced and when the feather latch teeth are in complete mesh the pitch lock teeth overlap but are out of contact with their locking faces 65 spaced. By making the feather latch of several small teeth of small axial extent and using the same number of pitch lock teeth with the tops of both sets of teeth having substantially the same axial spacing it is possible .to maintain the axial spacing of the pitch lock teeth 56, 58 while in the operating position shown in FIGS. 4 and 9 to a minimum so upon any malfunction such as overspeeding or other causes of loss of oil pressure in the chamber 50 the pitch lock. will have as small anaxial travel before becoming engaged as is possible. :PhlS quick acting feature of the pitch lock can be of vital importance where the propeller is rapidly reducing pitch due to some malfunction.

In order to prevent the pitch lock from meshing preventing reversing of the propeller a third cam 76 is provided on the member 44 in such a position that after the propeller passes the low pitch position of say 12 the cam 76 and the cam 64 will come into operative position to prevent axial movement of the member 44 and the meshing of the pitch lock teeth. When fluid under pressure is introduced into the chamber 50 piston 51 whose outer end is in contact with a flange carried by the member 44 is moved axially outward to move and maintain the member 44 out of contact with any of the elements of member 42 and member 42 may thus be freely rotated. The outward movement of the member 44 is limited by contact of a flange on the member 44 contacting a mating flange on the hub. Thus the normal or operating position of the member 44 and its axial relation to the member 42 is fixed and precisely determined. Hence, in the device incorporating the pluralityof small feather latch teeth of this invention it is possible to maintain a minimum distance axially between the cooperating pitch lock teeth to thus permit the pitch lock teeth to mesh with a minimum loss of time.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departing from its spirit and that various changes can be made which would come within the scope of the invention which is limited only by the appended claims.

We claim:

1. A pitch lock and feather latch comprising a pair of members each having a pitch lock portion and a feather latch portion, means moving said members a limited distance toward and from each other to bring them into and out of mating relation and means relatively positioning said members to permit selectively mating only said pitch lock portion or said feather latch portion, said moving means adapted to move both said feather latch and said pitch lock portions out of mating relation independent of said positioning means, said feather latch portion constructed and arranged, When in mating relation, to hold said pitch lock portion in overlapping but out of mating relation.

2;. A pitch lock and feather latch comprising a pair of members each having a pitch lock portion and a feather latch portion, means moving one of said members as a unit into and out of mating relation with the other member, including hydraulically actuated means having a limited movement and moving said one member out of feather latch mating relation, and means independent of said moving means for selectively mating only said pitch lock portion or said feather latch portion.

3. A pitch lock and feather latch comprising a pair of members each having a pitch lock portion and a feather latch portion, one of said members movable as a unit into and out of feather latch and pitch lock mating relation with the other member, a single acting hydraulic motor having a limited movement and when energized moving, and at is limit of movement holding, said one member out of both feather latch and pitch lock mating relation and other means preventing mating of one portion when the other portion is mated.

4. In an adjustable pitch propeller, a member having a continuous ring of undercut pitch lock teeth, an interrupted concentric ring of groups of feather latch teeth and a cam on one face, means for rotating said member around the axis of said rings in timed relation with propeller blade pitch change, a second member having a corresponding continuous ring of undercut pitch lock teeth, a corresponding interrupted concentric ring of groups of feather latch teeth and a corresponding cam on one face, means for holding said second member against rotation with respect to said propeller, said means for rotating said member positioning said groups of feather latch teeth and said groups of corresponding feather latch teeth in and out of juxtaposed position, means for yieldingly forcing said rings into teeth meshing engagement, said cams positioned to hold all of said teeth apart with substantially the same clearance while said groups of interrupted teeth are partially juxtaposed, said interrupted ring of groups of feather latch teeth when meshed, holding said pitch lock teeth apart.

5. In combination in an adjustable pitch propeller, a hub, 21 pair of concentrically arranged juxtaposed discs supported in said hub, a pitch changing motor rotating one of said discs on its axis in timed relation to propeller blade pitch changing movements, means preventing rotation of the other disc relative to said hub, said discs, having on their adjacent faces, arranged in axially extending concentric rows, respectively complementary pitch lock 6 i teeth, complementary feather latch teeth and complementary cam members, means independent of said pitch changing motor separating said discs a fixed distance and providing a fixed axial clearance between the respective pitch lock teeth the respective pitch latch teeth and the respec tive cam members whereby said one disc may be freely rotated without contact of said teeth or members, and means responsive to disabling of said separating means, and dependent on the relative rotary position of said discs, forcing said pitch lock teeth or said pitch latch teeth into mesh or said cam members into contact.

6. A combination as claimed in claim 18 in which the pitch lock teeth comprise a ring of undercut locking teeth and the feather latch teeth comprise an interrupted ring of non-locking teeth having the same pitch.

7. In combination in an adjustable pitch propeller, a hub, a pair of concentrically arranged juxtaposed discs supported in said hub, a pitch changing motor rotating one of said discs on its axis in timed relation to propeller blade pitch changing movements, means preventing rotation of the other disc relative to said hub, said discs, having on their adjacent faces, arranged in axially extending concentric rows, respectively complementary pitch lock teeth, complementary feather latch teeth and comple mentary cam members, means separating said discs, means responsive to disabling of said separating means forcing said pitch lock teeth into mesh, the tops of said feather latch teeth and said pitch lock teeth spaced substantially the same distance axially, said feather latch teeth having a shorter axial travel to completely mesh than said pitch lock teeth and when partially or completely meshed holding said pitch lock teeth separated, said cam members extending further axially than said feather latch and pitch lock teeth and when in contact holding all of said teeth separated and in which the pitch lock teeth comprise a ring of undercut locking teeth and the feather latch teeth comprise an interrupted ring of non-locking teeth radially aligned with the pitch lock teeth and shaped so that the pitch lock teeth lie within the radially viewed axially extending contour of the feather latch teeth.

8. A pitch lock and feather latch as claimed in claim 9 including cam means having a limited effective range and effective to hold the interrupted rows of non-locking teeth out of engagement a smaller fixed distance along said path in other juxtaposed positions upon failure of said motor.

9. A pitch lock and feather latch comprising a pair of juxtaposed members supported for relative movement along a path toward and away from each other and sup ported for relative movement substantially normal to said path, each member having a pitch lock portion comprising a row of interlocking teeth and a feather latch portion comprising an interrupted row of non-locking teeth arranged to mesh with corresponding teeth on the other member when the members are in selected'juxtaposed positions and are moved towards each other, a single acting motor, having a limited movement, and at its limit of movement separating said members and all of said teeth a fixed distance along said path in any of said selected juxtaposed positions and means urging said members into meshing relation. 7 I v 19. A pitch lock and feather latch comprising a pair of juxtaposed members supported for relative movement along a path toward and away from each other and supported for relative movement substantially normal to said path, each member having a pitch lock portion comprising a row of interlocking teeth and a feather latch portion comprising an interrupted row of non-locking teeth arranged to mesh with corresponding teeth on the other member when the members are in selected relative positions and are moved toward each other, power actuated means, having a limited movement, separating said members and all of said teeth along said path and means urging said members into meshing relation and in which the tops of the latch teeth and the tops of the lock teeth mating positions of the latch teeth the locking faces of the lock teeth are held out of engagement.

12. A pitch lock and feather latch are claimed in claim 11 in which the latch teeth have a smaller tooth height than the lock teeth. a 7

l3. Pitch control means for propeller including a combined feather latch and pitch lock mechanism having engaged and disengaged positions, power actuated means moving said mechanism, including the feather latch, to, and holding said mechanism in, a disengaged position independent of propeller pitch and a stop defining said disengaged position.

14. Mechanism as claimed in claim 13 including a single stop defining the disengaged position for'both the feather latch and the pitch lock.

15. Mechanism as claimed in claim 13 including cam means preventing said feather latch from moving into engaged position under selected conditions, said power actuated means holding both said cam means and said feather latch out of engagement.

16. Pitch control means as claimed in claim 13 in which the feather latch comprises juxtaposed complementary teeth having non-undercut contours and the pitch lock comprises juxtaposed complementary teeth having undercut locking contours movable into and out of engaged positions and in which the feather latch teeth are movable from engaged to disengaged position by said power actuated means with the propeller in a fixed feathered position.

17. A combination as claimed in claim in which the tops of the complementary feather latch teeth and said complementary pitch lock teeth are spaced substantially as the same distance axially, said feather latch teeth having a shorter axial travel to completely mesh than said pitch lock teeth and when partially or completely meshed holding said pitch lock teeth separated, said complementary cam members when held out of contact by said separating means spaced a smaller distance axially than said feather latch and pitch lock teeth and when in contact holding all of said teeth separated,

18. A pitch lock and feather latch comprising a pair of juxtaposed members supported for relative movement along a path toward and awayfrom each other and supported for relative movement substantially normal to said path, each member having a pitch lock portion comprising a row of interlocking teeth and a feather latch portion comprising an interrupted row of non-locking teeth arranged to mesh with corresponding teeth on the other member when the members are in selected relative positions and are moved toward each other, power actuated means, having a limited movement, separating said members and all of said teeth along said path, means urging said members into meshing relation, the tops of the corresponding latch teeth overlapping and the tops of the corresponding lock teeth overlapping along said path when the latch teeth are in meshed relation, and in that relation the tops of the corresponding latch teeth overlapping substantially the same distance that the tops of the lock teeth overlap.

References Cited by the Examiner UNITED STATES PATENTS 2,791,283 5/57 Lambeck et al -16032 2,940,527 6/60 Van Alstyne et al. 170-16032 2,998,849 9/61 Newton et al. 170-1602 3,003,567 10/61 Flaugh et. al 170-160.2 X

JULIUS E. WEST, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,18 ,819 June 8, 196

Philip E. Barnes et a1 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 43, for "is read its column 6, lin 12, for the claim reference numeral "18" read l7 Signed and sealed this 21st day of December 1965a (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

13. PITCH CONTROL MEANS FOR PROPELLER INCLUDING A COMBINED FEATHER LATCH AND PITCH LOCK MECHANISM HAVING ENGAGED AND DISENGAGED POSITIONS, POWER ACTUATED MEANS MOVING SAID MECHANISM, INCLUDING THE FEATHER LATCH, TO, 